Detection of high voltage diode_replacement of high voltage diode
1. High voltage diode detection
Measure both ends of the high voltage diode with a multimeter in the “R×10k” block, the forward resistance value is about 8-10kΩ, and the reverse direction is about 8-10kΩ. . . If the resistance values measured in the forward and reverse directions are the same, it means that the diode has been short-circuited or is seriously leaking.
For multimeters that detect high-voltage diodes, the battery inside should be above 9V (a 15V laminated battery is best), otherwise, when measuring its forward and reverse resistance values, the phenomenon will appear ∞, leading to misjudgment.
If you don’t have a multimeter, you can also use a wire to connect with a 40W bulb in series, and use its two ends to connect the two terminals of the diode and insert the power plug. If the diode is open, the bulb will not light up; if the diode is short-circuited, the bulb will stay on. Normal diodes should show unidirectional conductivity. When checking, it is best to have a known good diode for comparison, and pay attention to safety.
2. Replacement of high voltage diode
Before removing the high voltage diode, discharge the capacitor by short-circuiting the terminal, and then replace the diode. Pay attention to the polarity of the diode when replacing it. If the 6.3A fuse fuse is burned out due to a diode short circuit, the magnetron may also be injured at this time. If the high-voltage diode has a slight leakage, it will cause the cooking time of the food to be longer than the normal cooking time, but this phenomenon is rare, and the diode will eventually be damaged due to a long time.
After the high-voltage diodes for microwave ovens are damaged (open circuit or short-circuit), first choose the high-voltage diodes dedicated for microwave ovens, whose withstand voltage is better than the original tube (generally withstand voltage above 10000V and rated current above 1A). If there is no such kind of diode replacement, when other diodes are used instead, a high-voltage diode with a voltage that is about 2 times greater than the magnetron used should be selected for replacement. If there are no such accessories to replace for a while, you can also use 10 or more 1N4007 (1A, 1000V) diodes in series to replace them, and the effect is better.
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